1. Field of the Invention
The present invention relates to a synthesis of a 7-membered carbocarbocyclic compound having diexomethylene groups, more particularly to a synthesis of a 7-membered carbocyclic compound having diexomethylene groups, a novel compound having the structure represented by the following Chemical Formula 1, from trimethylsilanylmethyl-allenol derivative by the intramolecular Prins cyclization using Lewis acid. The 7-membered cyclic compound is a useful intermediate for synthesis of other multicyclic compounds.

In Chemical Formula 1, R1 is a C1 to C6 alkyl group, and R2 and R3 is respectively a hydrogen atom, or R1, R2 and R3 may be connected with neighboring substituents to form a 5 to 10-membered aliphatic or aromatic ring.
2. Description of the Related Art
7-membered carbocyclic compounds are important ingredients of biologically active natural substances and medicines. Recently, they are gaining interest in genetics because they are known to take part in cell division. For example, colchicine, which is known to be effective in treating gout [J. Org. Chem. 1985, 50, 3425–3427], is a tricyclic compound having a 7-membered ring. According to a recent report, colchicine derivatives have high cell toxicity against general cancer cells and their resistant MDRs.
Since 7-membered carbocyclic compounds have good biological activity, development of a 7-membered carbocyclic compound with a new structure is a prerequisite for drug researches.
A cyclic compound having diexomethylene groups can be expanded to other multicyclic compounds through Diels-Alder reactions. Therefore, the compound represented by Chemical Formula 1, which has diexomethylene groups, is a very useful intermediate in synthesizing a multicyclic compound via Diels-Alder reactions.